In the use of fluid storage and dispensing packages, the package may contain a fluid such as a high-purity reagent for use and semiconductor manufacturing. The fluid in such application in many instances is costly in character, and/or deleterious in effect if mis-dispensed. For such reason, it is desired that the reagent be conserved against any losses due to wastage, e.g., such as may occur through mis-dispensing of the fluid. Mis-dispensing of the fluid additionally may impair, or even render useless, a semiconductor device that is being manufactured. Further, many chemical reagents used in semiconductor manufacturing are very hazardous in character, e.g., being toxic, pyrophoric, corrosive or otherwise harmful in exposure to persons or processing equipment.
For these reasons, it is important for the fluid storage and dispensing package to be coupled with dispensing apparatus in a correct and reliable manner. This is particularly the case in many semiconductor manufacturing operations, where numerous chemical reagent packages are utilized in the course of wafer processing and semiconductor device fabrication, and each such fluid package is coupled to flow circuitry interconnecting the package with the semiconductor tool or other fluid-utilizing apparatus.
One type of package that has been widely utilized in the semiconductor manufacturing field is a liner-based fluid storage and dispensing package, in which a high-purity chemical reagent is contained in a flexible, polymeric liner, and the liner is disposed inside a rigid outer vessel commonly termed an “overpack.” In use, a dispensing assembly including a dispense head is coupled with the liner, and pressurizing gas is flowed into the overpack. The pressurizing gas exerts compressive force on the liner and progressively collapses the liner under the applied gas pressure, to effect dispensing of fluid from the liner. The dispense head in various embodiments is configured with a dip tube that extends downwardly into liquid in the liner when the dispensing assembly is coupled to the package and connected to suitable flow circuitry for the dispensing operation. The liner after being filled with fluid is typically sealed against atmospheric or ambient contamination by a membrane seal at the mouth of the liner.
An illustrative package of the above-described type is commercially available from ATMI, Inc. (Danbury, Conn.) under the trademark NOWPAK®.
In the coupling of a dispensing assembly with a liner package, it is critical that a dispensing assembly and associated flow circuitry be interconnected with a proper fluid storage and dispensing package, for the reasons discussed hereinabove. An intrinsic problem with such coupling of supply vessel and dispensing assembly is that an incorrect coupling, i.e., connection of a wrong dispensing assembly to a supply vessel, results in contamination when the sealing membrane on the package is punctured by the dip tube of the dispense head, and it then is discovered that a wrong dispensing assembly has been utilized. This can occur even if the mis-connection is immediately discovered, e.g., by inability to engage the dispensing assembly with any complementary connection structure on the fluid package. Although package systems have been developed in which mis-coupling of the dispensing assembly and the cap on a fluid storage and dispensing vessel is electronically effected, e.g., in vessels of the type commercially available from ATMI, Inc. (Danbury, Conn., USA) under the trademark NOWTRAK®, it is desirable to prevent such mis-connections of fluid delivery components in a simple, mechanical manner in applications in which electronic monitoring and control is excessively costly, impractical or otherwise infeasible.
It would therefore be a significant advance in the art to provide a coupling that provides a pre-connect verification of the correctness of a connection, which is applicable to fluid storage and dispensing packages of the foregoing type, to avoid circumstances in which dispensing equipment is contaminated with fluid from an incorrectly selected package.
Another issue of significance in the use of liner-based fluid storage and dispensing packages of the above-describe type, is the need to dispense as much of the fluid contents of the liner as possible, so that the fluid, which as discussed above may be costly in character, is efficiently utilized, without significant amounts of fluid being left in the liner at the conclusion of the dispensing operation.
In the original filling of liner packages, fluid conventionally is charged to the liner in a manner producing a nominal headspace that may for example be on the order of 5% of the interior volume of the liner, to accommodate expansion of the fluid during the subsequent storage and transport of the package. The headspace thereby provides a small volume of extraneous gas, e.g., air or other ambient gas, above the fluid in the liner. Although small in volume, this headspace gas is deleterious to the contained fluid.
A primary disadvantage of the headspace gas is that when the liner is subjected to external pressure in the dispensing operation, the resultingly compressed headspace gas solubilizes in the contained fluid to produce dissolved gas therein, in accordance with Henry's Law. The dissolved gas subsequently comes out of solution as the dispense pressure drops along the dispense train in the dispensing operation. This liberation of dissolved gas causes irregular and variable dispense profiles of the chemical reagent, e.g., a photoresist that is being flowed to a semiconductor manufacturing tool in a semiconductor manufacturing operation, resulting in the formation of potentially severe wafer defects, bubble formation on surfaces and subsequent popping of such bubbles, etc. Thus, the presence of significant headspace in the liner entails significant adverse consequences along the entire extent of the fluid delivery path including the final use of the fluid in the process system.
Despite this disadvantageous effect, headspace gas nonetheless has continued to be employed due to its utility as a “measuring fluid” in determining the approach to exhaustion of the fluid inventory in the liner during the latter stages of the dispensing operation. In the dispensing of liquid from a liner-based package containing headspace gas, the exhaustion of fluid from the liner causes headspace gas to be drawn into the suction train of the dispensing flow circuitry, and this entrainment of headspace gas results in the appearance of bubbles in the downstream liquid flow. Initial bubble appearance of the headspace gas is detected in the liquid flow and provides a useful indication that the liquid in the liner is approaching depletion.
The foregoing phenomenon has been usefully exploited in the provision of “first bubble” detectors for dispensing systems utilizing liner-based packages, in conjunction with the use of buffering reservoirs, to provide for continuity of fluid supply to the downstream tool or other location of use.
In such systems, the “first bubble” empty detector, upon sensing of the initial bubble, triggers the flow of a transitional supply of fluid from the buffering reservoir, so that the fluid-utilizing process is not interrupted, and can progress to completion. The reservoir may for example provide a volume on the order of 50 mL up to 200 mL or even more, of a photoresist material, so that when the liner-based package of photoresist material approaches depletion, as indicated by the appearance of the initial bubble in the downstream liquid, the supplemental volume of the buffering reservoir is tapped to provide sufficient fluid to finish a boat of wafers to which photoresist is being applied.
The “first bubble” sensing method of empty detection has proven reliable, but is associated with the inherent disadvantages of headspace gas becoming solubilized in the liquid in the liner and subsequently being released from the liquid during the dispensing operation, since such efflux of gas may give a premature indication of exhaustion of liquid from the liner, thereby preventing maximum utilization of liquid from the liner from being achieved, as well as interfering with the operation of downstream process equipment.
Accordingly, it would be a significant advance in the art to provide an empty detect system suitable for application to liner-based fluid storage and dispensing packages, which avoids the need for headspace gas, and concurrently provides an efficient and reliable detection of an approaching empty state of the liner package, with sufficiently early warning of such impending empty condition to accommodate switch-in of a fresh package of fluid for continued dispensing, without the requirement of an oversized buffering reservoir for providing continuity of fluid supply to the downstream fluid-utilizing location or facility.
Apart from the foregoing fluid inventory management issues, liner-based fluid storage and dispensing packages of the so-called “bag-in-drum” (BID), “bag-in-can” (BIC) and “bag-in-bottle” (BIB) types are in use, which engage with a dispensing assembly. An illustrative dispensing assembly for such purpose is the SMARTPROBE® connector commercially available from ATMI, Inc., Danbury, Conn., USA, and), which includes a dispense head (connector body) from which downwardly depends a dip tube that is inserted through a sealing membrane, termed a breakseal, in a fitment associated with the cap port of the liner package. After penetrating the membrane, the dip tube thereafter is in contact with the liquid in the liner, to effect dispensing when a pump is coupled with the dispense head. After breaking the membrane seal, pivot clamps associated with the dispense head are locked into place in order to securely position the dispense head on the liner overpack.
In order to subsequently remove the SMARTPROBE® from the fluid package, the user must press in the pivot clamps and exert upward force on the connector body, while concurrently holding the fluid package in place. Users having small hands generally experience difficulty in this disassembly procedure, particularly in pressing in the pivot clamps. Additionally, it is very difficult to break the static seal of the O-rings. Even after the static seal has been broken, the O-rings not infrequently catch on the breakseal. These factors, taken together, adversely impact the ease of use of such liner-based fluid storage and dispensing packages.
It would therefore be a significant advance to provide a SMARTPROBE®-type dispense assembly that is ergonomically enhanced in design, to obviate the foregoing difficulties.
Further, considering the shortcomings involved in prior use of liner-based fluid storage and dispensing packages, various problems are encountered with so-called breakseal or membrane elements that are pierced by the probe of the dispensing assembly when the connector is brought into engagement with the cap of the vessel.
First, breaking through the currently employed breakseal with the dispense probe produces particles that are carried into the contained chemical by the probe, thereby compromising the purity of the contained fluid. Second, the currently employed breakseal does not allow for material changes to match the needs of the chemical in the liner. Third, the currently employed breakseal does not allow vessels to be easily resealed for disposal. Fourth, the currently employed breakseal requires high force to insert the probe connector assembly, since the probe must pierce the membrane seal, which may entail resistance to the engagement of the connector with the vessel. Fifth, the seal integrity of the currently employed breakseal can be compromised by plastic creep induced relaxation of the seal clamping force.
For these reasons, a breakseal structure that would overcome such deficiencies would be a substantial advance in the use and reliability of breakseal-equipped vessels for fluid storage and dispensing.
In the use of liner-based fluid storage and dispensing packages, the dispense probe is inserted into a fluid in the liner, through a closure cap. In such packages, it is intended that the user not open the container, by removal of the cap. In some instances, due to inadequate training or accident, caps are unscrewed from containers with the probe still installed. This creates difficulties in removing the cap from the probe body and exposes the probe to contaminants, as well as providing the potential for subsequent mis-connection if the probe body and attached cap are then coupled with another container.
In various specific embodiments of the cap and probe, the cap and probe are key coded with respect to one another, to prevent insertion of a probe into an incorrect fluid storage and dispensing vessel. In certain instances, the cap and probe have been twisted off the vessel at the same time, rather than depressing pivot clamps at the side of the connector to permit the connector to be pulled upwardly and removed from the cap, and thereafter unscrewing the cap from the vessel.
It therefore would be a significant improvement to provide a closure cap for a liner-based fluid storage and dispensing package, in which the cap cannot be unscrewed from the vessel when the dispense probe has been inserted.
A further deficiency associated with the cap utilized in current liner-based fluid storage and dispensing packages relates to the pressurization opening in the cap, through which pressurizing gas is introduced into the vessel containing the liner, to exert pressure on the exterior surface of the liner, and thereby achieve pressure-mediated dispensing of fluid contained in the liner. Such pressurization opening in the cap is sealed by a tear tab, and removal of the tear tab to expose the opening for gas introduction frequently produces rough edges at the pressurization opening, due to the tear tab removal process. These rough edges in turn cause leaks to the O-ring seal of the dispense nozzle of the dispensing assembly.
In some instances of use of keycoded caps and probes in liner-based fluid storage and dispensing systems, users have been known to switch caps in order to defeat the keycode system, and occurrence that could lead to damage or destruction of products manufactured using fluid from such systems. As a result, it is desirable for caps of such systems to have a locking feature to prevent such switching, but which will still allow removal of the cap and replacement of same with a new cap when absolutely necessary. Such necessity may result from an incorrect keycoding of a fluid reagent by a chemical supplier, or performance of specialty chemical and process trials in which keycodes are not assigned, or accidental damage to a cap requiring its replacement.
In addition, the widespread commercial acceptance of the liner-based fluid storage and dispensing packages for high purity chemical reagents has resulted in a proliferation of such packages of varying types. Such multiplication of varieties of fluid packages also makes it necessary to provide packaging that prevents the mis-connection of caps to fluid storage and dispensing vessels that are inappropriate for such caps.